Valved cover for perforated-strip soffit vents

ABSTRACT

A valved cover is described for controlling air flow through perforated-strip-type soffit vents surrounding houses. The narrow, continuous vents are completely enclosed except for valved portholes in the cover, the flap valves being stiffly hinged to stay open (and quiet) in most weather to allow two-way ventilating air flow between outdoors and attic/roof space. The valved covers “harness” very strong winds: those on the the windward have their valves blown closed, blocking potentially destructive wind/rain entry into the attic/roof space, while those facing lee sides remain open so that the attic/roofspace is connected only to the wind-depressurized lee-side air and is therefore itself depressurized, helping hold the roof envelope together. The valved covers can be factory-mounted on the soffit panels and flat-folded for compact shipping and handling.

TECHNICAL FIELD

The invention controls air flow through perforated-strip soffit vents into and out of attics.

BACKGROUND OF THE INVENTION

Eave soffits are now often composed of solid boards having a vent composed of a strip of small, close-spaced perforations, the boards and their perforated strip vents extending around the house perimeter. Such a perforated strip's main advantage over traditional rectangular soffit vents is clear: no separate grille and insect screen are needed since the small perforations or slits serve both functions and yet provide more than adequate open area for attic/roof space ventilation. The solid sheet soffit—typically of fiber-cement or wood fiber composite boards of soffit width and considerable length—can be installed strongly for hurricane-prone regions and so finds favor there.

As with rectangular vents, however, hurricane-force winds can push rain water up through the perforations and carry it up into the roof space, sometimes ruinously. Further, such winds can pressurize the roof space through the vents in some fairly common house layouts, increasing the net pressure trying to push off roof sheathing, gables and the soffits themselves into the wind-induced depressurized areas outboard of the roof space envelope. Today's soffit vents increase the odds of the house being badly damaged in such ways.

Valving the soffit vents can help save the house: the valves can block rain entry while substantially reducing the net pressure trying to push the roof envelope apart. Valved vents are designed to rest open in normal conditions to allow two-way ventilation, but be pushed closed on the windward whenever an inward wind pressure differential reaches a certain strength, thereby blocking entry of wind and windborne rain. Since the lee-side vents continue to lie open, the roof space air connects only with the depressurized air there and so avoids pressurization and in fact (given that other roof vents are closed off or themselves valved) the roof space air is itself strongly depressurized in strong winds.

(The valved vent action can also help hold the whole roof structure down on the house, but only where the roof framing is of a once-typical type of rafter construction.)

In U.S. Pat. No. 6,484,459 B1, Platts discloses this concept of wind-actuated valved-vent depressurization of attic/roof space, and in “Quiet Acting Valved Vent” (Pat. Pend. Mar. 11, 2015) he and Russell describe a pleated design for rectangular soffit vent openings, offering almost completely unrestricted open area in normal and even most gusty conditions. That device, however, and indeed any prior-art valve device (as reviewed in Platts, Russell Mar. 11, 2015) is not readily or economically adaptable for covering perforated strip vents.

SUMMARY OF THE INVENTION

A basic object of the present invention, a valved cover for perforated-strip soffit vents, is to close and block wind-blown rain entry into the roof space when winds press excessively inwardly.

Another object is to help protect the integrity of a roof envelope by preventing significant pressurization of the roof space, regardless of wind direction and/or the presence of non-valved vents or air leakages into such space, by blocking wind entry through the soffit vents on the windward side or sides while allowing roof space air to exit freely through leeside valved vents.

A further object is to be usable in more strongly protecting the integrity of the roof envelope by depressurizing the roof space, generally requiring that significant air leakages be sealed and non-valved vents be blocked or valved (or otherwise designed to promote air exhaust) while roof space air exits freely through lee-side valved vents to the wind-depressurized air there.

A further object is to stay quiet even in commonly gusty wind conditions.

A still further object is to remain relatively simple and inexpensive overall, despite the bulkiness of the installed valved covers and their great length around a house, by allowing factory manufacture and assembly on soffit boards and yet be compactly shippable.

And of course a basic object is to provide unrestricted ventilation to a roof space in most weather conditions by remaining completely open to in-out air flow between outdoors and the roof space.

Terms: For greater certainty some terms are defined as follows: “House” here refers to a low-rise house or similar small building having a roof enclosing a space (“roof space”) thereunder. “Roof space” refers typically to the house attic along with the connected “soffit space” contained between roof overhang, soffit and the exterior wall portion above the soffit, more fully defined as the air space (no matter how shallow) enclosed by roof sheathing above, ceiling, soffit and wall portion below, and gables or such where present. “Roof space envelope” refers to just such enclosure. “Solid soffit” refers to a soffit constructed continuously around a house with long, solid panels (“soffit boards”) running parallel to the house wall, one long side being fixed to the wall and the other to the roof overhang's fascia structure. “Perforated strip vent” refers to a lengthwise vent strip of narrow width (typically a minor fraction of the soffit's width, and covering all or almost all of its length) running parallel to a house wall and composed of a multitude of closely spaced tiny openings together comprising sufficient open area for ventilating the roof space, the openings typically being round holes—but sometimes slits—so small that insects such as bees or spiders cannot get through. “Side” refers to a long side of such a strip vent; “end”, the short side across its end. (“Side edge” refers to an edge of a long side of a flat member.) “Porthole” refers to an opening of generally rectangular or round shape. “Flap valve” is that common type of valve where a thin flat plate has one side edge hinge-connected to, or near to, one side of an opening, the plate here resting away from the opening ready to be swung shut over it. “Fabric” means a cloth, limp and foldable. “Lee-side” or just “lee” refers to the area outboard of those sides of a house opposite to, or simply “around the corner” downwind from, the windward side(s). “Cover” refers to the main shell of the apparatus as now described; “valved cover” designates the whole apparatus.

Briefly described, the invention comprises a valved cover affixed over a perforated strip vent in a soffit board bounding a roof space to control air flow through said vent, comprising: a cover of vaulted cross-section enclosing an air space over the perforated strip vent, the cover having its side edges affixed to the soffit's solid surface along the sides of the perforated strip vent, with the cover's ends closed by end walls affixed to the cover and the soffit's solid surface to complete the cover's enclosure of the air space; at least one side slope or sidewall along the length of the cover having portholes offering a total open area similar to the enclosed perforated strip vent's open area; flap valves hinge-attached to the cover with a certain hinging stiffness and shaped and positioned sufficiently inboard of the portholes so that in most weather conditions the flap valves leave clear pathway for air flow inwardly or outwardly through the perforated strip vent and through the air space over the perforated strip vent and thence through the portholes to ventilate the roof space, but when subjected to outdoor wind pressures pushing inwardly toward the roof space with a certain strength the flap valves of the windward valved covers are pushed snugly closed across the portholes, blocking wind and rain entry. At the same time, those valved covers on the soffit vents around the wind-depressurized lee-sides of the house remain open, so that the roof space is connected only to the lee-side air and is itself depressurized, reducing net outward-acting air pressures trying to force apart the roof space envelope.

In one embodiment of the present invention the valved cover is comprised of: a first sidewall having its bottom edge hinge-connected to the soffit along a first side of the perforated strip vent; a top piece extending across much of the width of the perforated strip vent and having a first side edge hinge-connected to the top edge of the first sidewall; a second sidewall having its top edge hinge-connected to the second edge of the top piece and having its bottom edge hinge-connected to the soffit along the second side of the perforated strip vent, so completing a cover over the length and width of the perforated strip vent; portholes in the second sidewall offering a total open area greater than the enclosed perforated strip vent's open area, so that bursts of outgoing air cannot cause significant downward pressure on the valved cover; flap valves hinge-attached to the top piece and shaped and positioned sufficiently inboard of the portholes so that in most weather conditions the flap valves leave clear pathway for air flow inwardly or outwardly through the perforated strip vent; end walls made separately and ready to be inserted into and affixed to the cover and the soffit's solid surface to complete the cover's enclosure of the air space; wherewith the cover can lie flat-folded atop the soffit board to allow factory assembly thereon and yet allow compact packaging and shipping, then raised into final vaulted form and formed as the complete valved cover by inserting and securing the endwalls.

In a preferred embodiment of the present invention the valved cover is comprised of: a fabric top piece having a first side edge attached to the soffit along a first side of the perforated strip vent and its fabric extending across much of the width of the perforated strip vent and being there attached to a topside edge of a sidewall, the sidewall having its bottom side edge hinge-connected to the soffit along the second side of the perforated strip vent and so completing a cover over the length and width of the perforated strip vent; and the portholes in the sidewall offering a total open area greater than the enclosed perforated strip vent's open area, thereby minimizing the net pressure that roof space air can exert downward on the cover when lee-side depressurizations are strong; flap valves hinge-attached to the topside edge of the sidewall piece and shaped and positioned sufficiently inboard of the portholes so that in most weather conditions the flap valves stay open for air flow inwardly or outwardly through the perforated strip vent; a support plate positioned lengthwise under the cover and having one long side edge hinge-connected to the cover's underside and its opposite long side edge unattached on the perforated vent strip, the support plate being generously apertured; stops such as short pegs affixed along the perforated strip vent and protruding slightly up from the surface of same; end walls of fabric attached to or continuous with the fabric top and the soffit's solid surface; wherewith the whole valved cover can first lie flat-folded atop the soffit board to allow factory assembly thereon and yet allow compact packaging and shipping, and then be raised into final vaulted form and strongly supported there by the support plate, which has itself been rotated up by its hinged-connected long side edge, dragging its opposite long side edge forward over and just past the stops which then restrain the opposite long side edge from slipping backward, locking the plate into a nearly upright stance with its hinge-attached long side edge up and its other long side edge down.

These and other features and aspects of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings, in which like characters represent like parts.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevational cross-section of a valved cover mounted over a soffit's perforated strip vent.

FIG. 2 is a perspective sketch of a length of the valved cover mounted over the soffit's perforated strip vent.

FIG. 3 is a front elevational view of flap valves.

FIG. 4 is an elevational cross section of the valved cover mounted over a soffit's perforated strip vent under a windward-facing roof overhang subjected to strong wind.

FIG. 5 is an elevational cross section of the valved cover factory-mounted on a perforated strip-vented soffit and folded flat for shipping.

FIG. 6 is an elevational cross section of several pairs of perforated strip-vented soffits with their factory-mounted valved covers folded flat and stacked together for shipping.

FIG. 7 is an elevational cross section of a primarily fabric valved cover.

FIG. 8 is a view of perforated strip-vented soffit boards with valved covers at a building's corner, as seen from below.

FIG. 9 is a view of a multiple-slit type of perforated strip vent with valved covers, as seen from below.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Materials: While much or most of the valved cover could be made of thin metal, high-polymers will probably be best: polyvinyl chloride for the most part, offering suitably fire-safe performance; polypropylene for self-hinging valve parts, comprising very little fire load; polyester fabric where needed, again offering fire-safe performance. There's essentially no UV exposure, and little fatiguing flexing even of the valve hinges since they're designed to close only in uncommonly stormy conditions, as noted below.

FIG. 1 illustrates a preferred embodiment of the valved cover 1 covering a soffit's perforated strip vent 8 in a soffit 9. The valved cover's sidewall 2 and top 3 make up much of the cover as shown, while the taller sidewall 4 has room for portholes 6 (outermost dashed line) and is slanted inward. As discussed later, the sidewalls are joined to the soffit and the top by hinged connections 2′, 3′, and 4′. Hanging behind the portholes are flap valves 7 poised to control air flow between outdoors and roof space through the perforated strip vent 8. The flap valve 7 is shown in its rest position, the slant of 4 providing space between flap valve and porthole to help allow free air flow. The dashed lines off 7 indicate how it can swing closed over the portholes 6 when pushed by very strong winds, its hinged or self-hinging connection 7′ being of a certain stiffness to resist such movement in normally gusty conditions. Such stiffness prevents noise problems, and that is indeed important. (Further, hinge fatigue is prevented or greatly minimized, since the flap valve will seldom be bent much. Self-hinging polypropylene would be suitable.) The valved cover 1 will be subjected to considerable upward pressure in hurricane-force winds, so its attachment to the soffit 9 must be strong and may preferably be achieved by having flanges formed with anchor fingers, 10, adhered to the soffit 9 and down into holes or grooves therein. The perforated strip vent 8 may itself be made wider to provide holes for the fingers 10. Epoxy or urethane adhesive may provide sufficient anchorage at 10, without the fingers.

FIG. 2 shows the valved cover 1 covering across and along a length of perforated strip vent 8 on a soffit 9, as viewed from above, with one end wall 5 shown ready for insertion. (Not visible is a similar end wall at the far end of 1.) The view through the portholes 6 shows that the flap valves 7 have open area between them as well as under them for free air flow.

That openness is further illustrated in FIG. 3, showing how the valve assembly 7 has individual flaps separated by spaces 7″. The sketch also shows how the flap valves may be connected along their tops to help ensure they respond smoothly together to wind pressures.

In FIG. 4, the valved cover 1 is shown in action on the windward side of a house, with portholes 6 shown closed by flap valves 7 to block a strong wind's upward-pushing air flow (arrow) and so block any rain-carrying or roof space pressurizing effects that such inward air flow can inflict. The (+) signs denote that the wind pressure exerted under the soffit is equaled in the air space enclosed by the valved cover. The roof and soffit spaces RS and SS are depressurized (−) since the lee-side valved covers remain open to the lee's wind-depressurized air. The net air pressure upwards on the valved cover 1 is therefore even stronger than the wind's velocity pressure (+). The vaulted form of the cover 1 can take the extreme load efficiently, the top 3 bending upwards a little.

On the lee-side, however, sudden depressurizations“pulling” a first rush of air out of the roof space can briefly press strongly downward on 1, potentially presenting a structural problem; but that pressure is minimized, according to the invention, by making the open area of the portholes 6 significantly larger than that of the vent 8, so keeping the air pressure within the cover-enclosed space almost equal to that in the soffit space/roof space, SS and RS, in such instances. (That porthole area is easy to achieve: perforated strip vents typically offer just 5 sq. in. of opening per foot of length.) Further, such an outgoing rush of air from the roof space is very short-lived, in that little air can flow out when little replacement air can flow in.

As suggested by the arrow below the soffit, the valved cover's closure stalls upward air flow significantly below the soffit. In hurricane-force winds the rain's upward momentum from below that stalled region can carry some up against the underside of the soffit 9, but there's no pressure differential/air flow to carry the splatter through the perforations 8.

Also apparent in FIG. 4 is a design constraint regarding perforated strip vent covers 1: their height is limited by the roof frames RF above (whether rafter or truss chord), since they must pass under them. Further, building practitioners prefer to place soffit vents close to the outer edge of the soffit, supposing that such placement improves ventilation. Especially with low slope roofs (even lower than illustrated here) the sloped vaulted form of 1 is ideal to fit within such vertically limited space, with the low sidewall 2 facing the roof edge while the higher sidewall 4 faces the roof space SS-RS and allows sufficient room for ports 6.

The valved vents as shown above are “nestably” shaped, which would allow economically compact shipping to distributors and final construction sites separately from the soffit boards. That, however, would leave some demanding work for the job site: attaching the valved vents to the soffit boards. Costs would be increased and quality assurance could be undermined even if done in ideal weather. Complete factory manufacture is strongly desirable.

FIGS. 5 and 6 show how factory assembly of the valved cover on the soffit board is made practicable by having the valved vent 1 flat-folded and affixed to the soffit board 9, allowing compact, economical packaging and shipping while still reducing costs and complexities on site. As shown previously, in FIG. 1, the sidewalls 2 and 4 are hinge-connected to the top 3 and to anchorages 10, and of course the flap valve 7 is hinge-connected to the top 3, allowing flat-folding. FIG. 6 suggests that the complete valved soffit products can be stacked in pairs for nesting: one soffit 9 in each pair being upside down with valved cover underneath, the other being right side up with its valved cover on top. The valved covers are offset by this “flip”, so just one space per pair of soffit boards accommodates both valved covers as shown. (Perforated strip vents are normally positioned near the outer side of soffit boards, purportedly to provide better ventilation by having the vent close to the outer edge of the roof overhang; that provides the offset.)

Unpackaged at the job site, the flat-folded valved covers must first be raised into their operative form before installing the soffits. In the embodiment as shown in FIG. 1, a push to the right can do that, and insertion of the end walls 5, FIG. 2, then holds the valved cover properly. However, such support at the ends might not adequately maintain the form of longer valved covers (commonly being 8 to 12 feet long, on standard perforated-strip-vented soffit boards); perhaps thin metal springs could help, placed to rotate at least one sidewall up into position. A more certain support solution is noted next.

FIG. 7 shows a primarily fabric embodiment of the valved cover, also allowing flat folding compactness for shipping economy from factory to site and reduction of on-site work. The top 3 and the end walls (not shown) are of strong, foldable fabric. The sidewall 4 is still of rigid material, hinge-connected at 10. A plate or line of plates 11 is hinge-connected to the junction of the top 3 and the sidewall 4 as shown, the plate being well apertured (not shown) to allow free air flow through it. When the valved vent cover 1 is raised from the flat into its operative form (here using a soft tab 4″), the hinge-connected edge of the plate 11 is pulled up too and the bottom side edge is dragged forward and over a stop 12, the bottom side thereby being prevented from slipping backward so the plate is fixed upright to support the valved vent cover 1. (The plate or line of plates 11 might of course be used to further support the foldable valved vent cover of FIG. 6.)

The flap valve 7 in FIG. 7 may best be bottom-connected at 7′, hinged or self-hinged to spring up and rest open at an angle from the porthole 6 unless blown further upward (dashed lines 7) by sufficiently strong wind pressure. (Then the top 3 would arch upwards as shown by its dashed line, its fabric under tension.)

Installing continuous soffits around any house will always require cut-and-fit at some corners and other stops. On-site cutting across a standard board and its valved cover could be done, with the enclosure of the cut-off valved cover then “made good” with an extra end wall plugged in—but not easily. A much simpler procedure is shown in FIG. 8, looking up from below at soffits covering eaves around an external corner at the left and part of an internal corner, right. The soffit boards 9 with perforations 8 and (dashed lines) valved covers 1 are shown terminating at the external corner, needing no trimming or extension of length at that point. (The soffit installation could normally start at such corners, advantageously.) Further to the right along one wall, a standard length board 9 has ended short of an internal corner, as has another standard length board 9 just around that corner. How fill such gaps? Since perforated-strip-vented soffits present considerably more vent area than is deemed necessary around a house, a few non-vented soffit boards could be supplied with every job shipment. These could then provide site-cut lengths such as 9′ to complete all sides and corners, needing no vent cover over those short lengths of impervious soffit. Such non-vented fill-in soffits 9′ could best have indentations 8′ on their undersides as shown, to maintain the attractive appearance of a continuous perforated strip vent.

Building codes for storm-prone regions may generally (and arbitrarily of course, wastefully) specify that solid soffit boards span no more than 2 ft; if eaves are wider than that, cross framing must be laboriously installed between the house wall and fascia at 2 ft. intervals to support the soffit boards. Such frames complicate the use of valved vent covers. FIG. 9 shows another common type of perforated-strip-vented soffit board 9 that can simplify this: the vented area is a strip of rectangles perforated with close-together slits, 8″, with solid portions of soffit between the ends of the perforated rectangles, as shown. Factory applied over the spaced rectangular vents 8″, short valved vent covers 1 can readily fit up between the cross framing (not shown) as the soffit boards are installed. (Economics may favor the fabric type covers of FIG. 7 for such short valved vent covers.)

While this invention has been described with respect to just a few similar embodiments thereof, it will be appreciated by those skilled in the art that various changes in form and detail thereof may be made without departing from the spirit of the claimed invention. 

I claim:
 1. A valved cover affixed over a perforated strip soffit vent to control air flow through said vent, comprising: a cover enclosing an air space over the perforated strip vent, the cover having its side edges affixed to the soffit's upper surface along the long sides of the perforated strip vent; an end wall closing each end of the cover, each end wall being affixed to the cover and the soffit's upper surface to complete the cover's enclosure of air space over the perforated strip vent; portholes in at least one side slope of the cover, the portholes offering a total open area similar to the perforated strip vent's open area and so allowing ventilating air flow inward and outward between outdoors and a roof space; flap valves positioned inboard of the portholes and hinge attached to the cover, the hinging having a certain stiffness holding the flap valves away from the portholes; whereby in most weather conditions the flap valves remain quiet and leave clear pathway for air flow inwardly or outwardly through the perforated strip vent and through the air space over the perforated strip vent and thence through the portholes to ventilate the roof space, but when subjected to outdoor wind pressures pushing inwardly toward the roof space with a certain strength the flap valves are pushed closed across the portholes, thereby blocking wind and rain entry into the roof space; while at the same time those soffit vents located around the wind-depressurized lee-sides of the house, similarly covered with the valved vent covers, remain open so that the roof space is connected only to the lee-side air so the roof space is itself depressurized, reducing net outward-acting air pressures trying to force apart the roof space envelope.
 2. A valved cover according to claim 1 comprising: a first sidewall having its bottom edge hinge-connected to the soffit along a first side of the perforated strip vent; a top piece extending across much of the width of the perforated strip vent and having a first side edge hinge-connected to the top edge of the first sidewall; a second sidewall having its top edge hinge-connected to the second edge of the top piece and having its bottom edge hinge-connected to the soffit along the second side of the perforated strip vent; portholes in the second sidewall offering a total open area greater than the perforated strip vent's open area, thereby minimizing the net pressure differential that roof space air can exert downward on the valved cover when leeside depressurizations are strong; flap valves hinge-attached to the top piece with the hinging having a certain stiffness; end walls insertable into each end of the valved cover; wherewith the valved cover less its end walls can be folded flat atop the soffit board for compact packaging and shipping to the job site, where before installation on the house the valved cover is raised into its vaulted form enclosing an air space above the perforated strip vent and the end walls are inserted and affixed to support the valved cover's vaulted form and complete its enclosure of the air space.
 3. A valved cover according to claim 2, wherein: the end walls are made of fabric permanently attached to the ends of the valved cover and the soffit thereunder; a support plate is positioned lengthwise under the valved cover, the plate having one side edge hinge-connected to the cover's underside, the plate's opposite side edge resting unattached atop the perforated vent strip, the plate's width being the desired final height of the valved cover and the plate being generously apertured to allow air to flow freely through it; stops such as short pegs are affixed along the perforated strip vent under the support plate; wherewith the complete valved cover can be folded flat atop the soffit board for compact packaging and shipping to the job site, where before installation on the house the valved cover is raised into its vaulted form enclosing an air space above the perforated strip vent, thereby pulling up the hinge-connected side edge of the support plate and dragging forward the support plate's opposite side edge partly across the perforated strip vent and over and just past the stops, the stops then keeping the plate's opposite side edge from slipping backward and so locking the plate into a suitably upright stance to support the valved cover's vaulted form.
 4. A valved cover according to claim 2 wherein a single fabric piece replaces the first sidewall and the top piece, the fabric piece having a first side edge attached to the soffit along a first side of the perforated strip vent, the fabric piece thence extending across much of the width of the perforated strip vent and being there attached to the topside edge of the opposite sidewall, and the ends of the fabric piece forming the fabric end walls to complete the valved cover attached to the soffit panel to enclose the perforated strip vent, wherewith the complete valved cover can be folded flat atop the soffit board for compact packaging and shipping to the job site, where the valved cover is raised into its vaulted form enclosing an air space above the perforated strip vent, thereby pulling up the hinge-connected side edge of the support plate and dragging forward the support plate's opposite side edge partly across the perforated strip vent and over and just past the stops, the stops then keeping the plate's opposite side edge from slipping backward and so locking the plate into a suitably upright stance to support the valved cover's vaulted form.
 5. A method for improving a house's resistance to damage from hurricane-force winds and rains by controlling air flow through perforated-strip vents of soffit boards enclosing the eaves around the house, comprising steps of: providing valved covers for the perforated strip vents, the valved covers having a plurality of portholes therethrough, with a plurality of flap valves operably attached to an inner surface of the cover inboard of and spaced away from the portholes, said flap valves being stiffly hinged to remain open and quiet except when subjected to very strong inward-acting wind pressures which close the flap valves over the portholes to block wind and rain entry therethrough; affixing the valved covers atop the soff it boards over their perforated strip vents to enclose an airspace bounded by the valved cover and said vent; folding the valved covers flat atop the soffit boards, thereby allowing compact packaging and shipping to the house; thence unfolding the valved covers and supporting them in their vaulted form over the perforated strip vents; and installing the soffit boards integral with the valved covers to enclose the eaves around the house; whereby the flap valves of the valved covers leave the portholes open in most weather conditions to allow two-way air flow between outdoors and roof space through the perforated strip vents to provide roof space ventilation, but those windward flap valves facing a certain amount of inflow pressure from windstorms are pushed closed over their portholes, that closure blocking wind/rain entry through the soffits' perforated strip vents; while at the same time the valved covers on the lee-side remain open so that the roof space air connects only with the wind-depressurized lee-side air and is therefore itself depressurized, substantially reducing net outward forces induced by wind action on the roof envelope and so helping keep the envelope intact.
 6. A valved cover according claim 1 formed flexibly to allow flat-folded installation on the perforated strip soffit vent for compact packaging and shipping to a job site, and equipped to be raised and affixed into a vaulted form enclosing an air space above the perforated strip vent. 